Fun fact: The centrifuge set in the Discovery was 'real', in that it was actually built complete, all the way around, and rotated just like a real life version would.

Well, not just like. The real thing would've rotated at a constant velocity to create a sensation of weight in freefall conditions, with "down" being outward from the axis in every direction. The centrifuge set only rotated as needed when the actors were walking or jogging through it, so that they'd stay on the bottom; when they were standing still, so was the centrifuge. So it was using real gravity to fake the appearance of fake gravity.

__________________Christopher L. Bennett Homepage -- Site update 11/16/14 including annotations for "The Caress of a Butterfly's Wing" and overview for DTI: The Collectors